THE OBJECTIVES OF THIS PROGRAM INCLUDE THE FOLLOWING: 1) To expand our understanding of fetal nutrition and metabolism, particularly in the areas of amino acid uptake and studies of alternate carbon sources other than glucose. 2) Evaluation of the impact upon fetal metabolism of maternal starvation and of maternal hypoxia. 3) A comparison of cerebral blood flow regulation and cerebral metabolism in fetal and postnatal life. 4) Evaluation of placental growth and functional maturation by studies which relate cell number, cell type, and surface area versus measurements of placental clearance and umbilical uptake of substrates. 5) A continued study of the factors regulating blood flow to reproductive tissues including, specifically, the role and mechanism of action of estrogens upon both mammary and uterine blood flow. 6) The role of glycoproteins synthesized by trophoblast, particularly HCG, in immunosuppression and thus in implantation and early trophoblast development. 7) An evaluation of the metabolic differences between SGA infants and preterm infants, and the impact of supportive care measures upon immediate and long-term morbidity. 8) A continuation of ongoing studies for the prediction of high-risk pregnancy, with special emphasis on methods of distinguishing preterm versus SGA infants prior to delivery.